linux-kernel - Re: [PATCH v2 1/3] hwmon: (lm90) Add power control

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Date:	Thu, 8 Aug 2013 17:26:14 +0800
From:	Wei Ni <wni@...dia.com>
To:	Alexander Shiyan <shc_work@...l.ru>
CC:	"khali@...ux-fr.org" <khali@...ux-fr.org>,
	"linux@...ck-us.net" <linux@...ck-us.net>,
	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	Matthew Longnecker <MLongnecker@...dia.com>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/3] hwmon: (lm90) Add power control

On 08/08/2013 03:13 PM, Alexander Shiyan wrote:
>> The device lm90 can be controlled by the vdd rail.
>> Adding the power control support to power on/off the vdd rail.
>> And make sure that power is enabled before accessing the device.
>>
>> Signed-off-by: Wei Ni <wni@...dia.com>
>> ---
>>  drivers/hwmon/lm90.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 49 insertions(+)
>>
>> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> [...]
>> +static void lm90_power_control(struct i2c_client *client, bool is_enable)
>> +{
>> +	struct lm90_data *data = i2c_get_clientdata(client);
>> +	int ret;
>> +
>> +	if (!data->lm90_reg)
>> +		return;
>> +
>> +	mutex_lock(&data->update_lock);
>> +
>> +	if (is_enable)
>> +		ret = regulator_enable(data->lm90_reg);
>> +	else
>> +		ret = regulator_disable(data->lm90_reg);
>> +
>> +	if (ret < 0)
>> +		dev_err(&client->dev,
>> +			"Error in %s rail vdd, error %d\n",
>> +			(is_enable) ? "enabling" : "disabling", ret);
>> +	else
>> +		dev_info(&client->dev, "success in %s rail vdd\n",
>> +			 (is_enable) ? "enabling" : "disabling");
> 
> dev_dbg() ?

As Guenter said, I will remove these messages, and remove this function,
the code will be more clean.

> 
>> +
>> +	mutex_unlock(&data->update_lock);
>> +}
>> +
>>  static int lm90_probe(struct i2c_client *client,
>>  		      const struct i2c_device_id *id)
>>  {
>> @@ -1406,6 +1434,20 @@ static int lm90_probe(struct i2c_client *client,
>>  	i2c_set_clientdata(client, data);
>>  	mutex_init(&data->update_lock);
>>  
>> +	data->lm90_reg = regulator_get(&client->dev, "vdd");
>> +	if (IS_ERR_OR_NULL(data->lm90_reg)) {
> 
> What about deferred probe?
> if (PTR_ERR(data->lm90_reg) == -EPROBE_DEFER)
> return -EPROBE_DEFER;

Oh, yes, I should add it.

> 
>> +		if (PTR_ERR(data->lm90_reg) == -ENODEV)
>> +			dev_info(&client->dev,
>> +				 "No regulator found for vdd. Assuming vdd is always powered.");
> 
> On my opinion it is unnecessary message.
> 
>> +		else
>> +			dev_warn(&client->dev,
>> +				 "Error [%ld] in getting the regulator handle for vdd.\n",
>> +				 PTR_ERR(data->lm90_reg));
> 
> Ditto.

I will remove these log messages.

> 
>> +		data->lm90_reg = NULL;
> 
> You can just use !IS_ERR(data->lm90_reg) macro in the future,
> rather than set this to NULL.

Yes, it's better, I will do it.

> 
> [...]
> 
> ---
> 

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